It’s popular to break down how offenses perform inside the red zone—the hypothetical area inside the opponent’s 20-yard line—but the “real” red zone is inside the opponent’s 10-yard line. That’s where the ability of an offense to move the football as usual breaks down, anyway. While passing is generally suitable to running in most areas of the field, a strong running game is a necessity to thrive near the goal line. When the field shrinks and defenders don’t need to worry about receivers beating them deep, the benefits of passing over running diminish.

That’s particularly true on first down. On a league-wide basis, coaches called for a first-down run 52.2 percent of the time in 2012. As a whole, most teams could increase offensive efficiency by passing a whole lot more on first down in most areas. Jason Garrett’s first-down play-calling has generally been pretty good—he called for a pass on 58.7 percent of the Cowboys’ first downs this year—but he actually passes too often in the “real” red zone.